Electrical pathway intermittent fault detection

ABSTRACT

Testing to detect intermittent electrical pathways is described. Applied currents may be reversed to fully test all components of a workpiece. Various testing methodologies may be employed. These methodologies may include Time Domain Reflectometry (TDR), mechanical agitation, dark current/voltage testing, (dark IV), i.e., electrical testing of a workpiece using applied electricity, and thermographic imaging, e.g., infra-red thermal imaging. The sensed voltage during agitation may be compared to a benchmark voltage to determine whether or not an intermittent failure exists.

BACKGROUND

Photovoltaic (PV) cells, commonly known as solar cells, are devices forconversion of solar radiation into electrical energy. Generally, solarradiation impinging on the surface of, and entering into, the substrateof a solar cell creates electron and hole pairs in the bulk of thesubstrate. The electron and hole pairs migrate to p-doped and n-dopedregions in the substrate, thereby creating a voltage differentialbetween the doped regions. The doped regions are connected to theconductive regions on the solar cell to direct an electrical currentfrom the cell to an external circuit. When PV cells are combined in anarray such as a PV module, the electrical energy collected from all ofthe PV cells can be combined in series and parallel arrangements toprovide power with a certain voltage and current.

Numerous electrical pathways exist in a PV module. These pathwaysinclude: electrical components themselves—including their internalsub-components—leads emanating from electrical components; systemtraces; system busses; and connections therebetween. System, component,and sub-component connections may be soldered connections or connectionswithout solder, such as snap-fit mechanical connections. When any ofthese pathways fail, the PV module operation and output may be hinderedor completely lost depending upon the number and/or severity of thepathway failure. These failures may be permanent failures orintermittent failures. Intermittent pathway failures may be consideredelectrical pathways that are operational during periods of time andunintentionally inoperable during other periods of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic of a laminate photovoltaic workpieceunder forward bias testing according to some embodiments.

FIG. 2 illustrates a schematic of a laminate photovoltaic workpieceunder reverse bias testing according to some embodiments.

FIG. 3 illustrates process elements for workpiece testing as may beemployed in some embodiments.

FIG. 4 illustrates process elements for time domain reflectometry (TDR)workpiece testing as may be employed in some embodiments.

FIG. 5 illustrates process elements for non-illumination current/voltage(dark IV) workpiece testing as may be employed in some embodiments.

FIG. 6 illustrates process elements for infra-red workpiece testing asmay be employed in some embodiments.

FIG. 7 illustrates process elements for mechanical agitation workpiecetesting as may be employed in some embodiments.

FIG. 8 illustrates an exemplary testing system manager according to someembodiments.

FIG. 9 illustrates a schematic of a laminate photovoltaic workpiece asmay be employed in some embodiments.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter of theapplication or uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

This specification includes references to “one embodiment” or “anembodiment.” The appearances of the phrases “in one embodiment” or “inan embodiment” do not necessarily refer to the same embodiment.Particular features, structures, or characteristics may be combined inany suitable manner consistent with this disclosure.

Terminology. The following paragraphs provide definitions and/or contextfor terms found in this disclosure (including the appended claims):

“Comprising.” This term is open-ended. As used in the appended claims,this term does not foreclose additional structure or steps.

“Configured To.” Various units or components may be described or claimedas “configured to” perform a task or tasks. In such contexts,“configured to” is used to connote structure by indicating that theunits/components include structure that performs those task or tasksduring operation. As such, the unit/component can be said to beconfigured to perform the task even when the specified unit/component isnot currently operational (e.g., is not on/active). Reciting that aunit/circuit/component is “configured to” perform one or more tasks isexpressly intended not to invoke 35 U.S.C. § 112(f) for thatunit/component.

“First,” “Second,” etc. As used herein, these terms are used as labelsfor nouns that they precede, and do not imply any type of ordering(e.g., spatial, temporal, logical, etc.). For example, reference to a“first” mechanical vibration test does not necessarily imply that thismechanical vibration test is the first test in a sequence; instead theterm “first” is used to differentiate this mechanical vibration testfrom another mechanical vibration test (e.g., a “second” mechanicalvibration test).

“Based On.” As used herein, this term is used to describe one or morefactors that affect a determination. This term does not forecloseadditional factors that may affect a determination. That is, adetermination may be solely based on those factors or based, at least inpart, on those factors. Consider the phrase “determine A based on B.”While B may be a factor that affects the determination of A, such aphrase does not foreclose the determination of A from also being basedon C. In other instances, A may be determined based solely on B.

“Coupled”—The following description refers to elements or nodes orfeatures being “coupled” together. As used herein, unless expresslystated otherwise, “coupled” means that one element/node/feature isdirectly or indirectly joined to (or directly or indirectly communicateswith) another element/node/feature, and not necessarily mechanically.

“Inhibit”—As used herein, inhibit is used to describe a reducing orminimizing effect. When a component or feature is described asinhibiting an action, motion, or condition it may completely prevent theresult or outcome or future state completely. Additionally, “inhibit”can also refer to a reduction or lessening of the outcome, performance,and/or effect which might otherwise occur. Accordingly, when acomponent, element, or feature is referred to as inhibiting a result orstate, it need not completely prevent or eliminate the result or state.

In addition, certain terminology may also be used in the followingdescription for the purpose of reference only, and thus are not intendedto be limiting. For example, terms such as “upper”, “lower”, “above”,and “below” refer to directions in the drawings to which reference ismade. Terms such as “front”, “back”, “rear”, “side”, “outboard”, and“inboard” describe the orientation and/or location of portions of thecomponent within a consistent but arbitrary frame of reference which ismade clear by reference to the text and the associated drawingsdescribing the component under discussion. Such terminology may includethe words specifically mentioned above, derivatives thereof, and wordsof similar import.

In the following description, numerous specific details are set forth,such as specific operations, in order to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to one skilled in the art that embodiments of the presentdisclosure may be practiced without these specific details. In otherinstances, well-known techniques are not described in detail in order tonot unnecessarily obscure embodiments of the present disclosure.

This specification describes exemplary testing for intermittentelectrical pathways followed by a more detailed explanation of variousembodiments of testing methodologies as well as devices and systems thatmay be employed when testing. Various examples are provided throughout.These examples may be combined in part or in whole with other examplesas well as with other features or processes not explicitly describedherein but consistent with the teachings of the disclosure.

Embodiments may include an end of line electrical pathway testing systemthat uses a monitoring current with rapid voltage sensing frequencies tomeasure interconnections between photovoltaic cell circuits, laminatedsolar modules or other workpieces, for intermittent electrical pathwayssuch as solder connections and diode functionality. Testing inembodiments may occur on partially assembled as well as fully assembledworkpieces. In other words, electrical workpiece connections may betested even though still more electrical connections remain to beadded—a fully assembled workpiece, with each of its intended connectionsmay also be tested. For example, a grouping of cells of a photovoltaiclaminate may be tested before final assembly of the photovoltaiclaminate as well as after final assembly of the photovoltaic laminate.The connections between photovoltaic cells, rather than connectionswithin the cells themselves, are preferably targets for the intermittenttesting of embodiments.

Various testing methodologies may be employed in embodiments. Thesemethodologies may include Time Domain Reflectometry (TDR), mechanicalagitation, dark current/voltage testing, (dark IV), i.e., electricaltesting of a workpiece using applied electricity, and thermographicimaging, e.g., infra-red thermal imaging. These methodologies may beapplied individually as well as in various combinations, and may beapplied in various orders. These methodologies may be applied underforward bias electrical loading conditions of the workpiece as well asreverse-bias electrical loading conditions of the workpiece. Reversingthe electrical loading on a workpiece from test to test or withintesting methodologies may allow for testing or otherwise isolatingelectrical connections of a workpiece for testing not otherwise testableas well as for determining which, if any, electrical connections havefailed. For example, a photovoltaic laminate with diodes may containone-way electrical pathways that only become active under shadedconditions, these one-way pathways may not be activated in each testingcondition and thereby testable unless current is applied in a forwardbias during testing or a reverse bias during testing. Thus, testing inembodiments may first be conducted with current flowing in one directionand, tested again, with current reversed. For example, in certain PVcircuits, laminates or modules being tested may be run both in reversebias to measure diode function and solder joint condition in junctionboxes. Then, a test may be run in the forward current bias direction totest for missing or broken solder connections on a center lane to busribbon joint, for example, as well as other electrical pathways.

As noted above, a testing system or process in embodiments may use TimeDomain Reflectometry (TDR) to test electrical connections and to isolatethe location of failed or passing electrical connections. In TDRembodiments, varying electrical signals may be placed on a workpiece andsubsequently measured for the resulting reflected signals experiencedafter passing though or otherwise interfacing with one or moreconnections. The resulting signals are considered to result from thehigh damping effects introduced by passing by or through solar cells andother diodes. The resulting dampened, reflected signals may be measuredand used to determine if any electrical connections in the workpiecehave failed and which ones have failed. Processes in embodiments maymeasure electrical signals reflected back from a connection to be testedmuch like sending an acoustic signal underwater and listening for thereflected signal. Processes in embodiments may employ activated diodes,which have been turned on or otherwise biased with a power supply. Inother words, during testing, diodes to be tested may receive an appliedvoltage or current from a power supply so as to amplify the reflectedsignal during TDR testing. Embodiments may also apply differentelectrical frequencies over a spectrum of frequencies when testing. Thisspread spectrum TDR testing may serve to promote testing accuracy byproviding testing at numerous testing frequencies. This spread spectrummay, accordingly, provide to increase the ability to determine reflectedsignals as well as to test electrical connections that may provideindicia of failure at one testing frequency but not another frequency.Whether the reflected signal or downstream signal is collected,embodiments may employ these signals to determine whether a workpiececontains functioning or impaired electrical connections.

As also noted above, a testing system or process in embodiments may usea percussive agitation from a vibration generator to stimulate a changein electrical signal during the presence of an intermittent connectionbeing tested for. Exemplary agitation tests may be performed withforward and reverse currents in order to test one-way electricalpathways in a workpiece being tested. As noted above, a photovoltaiclaminate with diodes may contain one-way electrical pathways that onlybecome active under shaded conditions, these one-way pathways may not beactivated and thereby testable unless current is applied in a forwardbias during testing or a reverse bias during testing. Thus, percussiveagitation testing may first be conducted with current flowing in onedirection and, tested again, or a third or fourth time, with currentreversed.

As further noted above, a testing system or process in embodiments mayemploy dark current/voltage testing, (dark IV or non-illuminated IV).This dark IV applied electricity may, too, be applied in a forward biasas well as in a reverse bias of the workpiece. Accordingly,non-illumination applied current and voltage testing may be conductedwith both forward bias current and reverse bias current. In eachinstance resistance changes, current changes, or other measurableelectrical properties may be measured to determine electrical connectionfaults and failures. In these and other embodiments, open joints may bemore readily determined by forward bias testing while reverse biastesting may be more suitable for determining intermittent or partiallycomplete electrical connections. When testing PV modules, whetherpartially or fully assembled, hardware used for flash testing PV modulesmay also be employed to sense and measure resulting resistances fromdark IV testing of embodiments.

As also noted above, a testing system or process in embodiments mayemploy infra-red imaging or other thermal imaging. Here, a current maybe applied to a workpiece in forward and/or reverse bias while theworkpiece is viewed using infra-red camera(s) or other thermographicsensors. The presence and/or absence or quantity of heat signatures maybe used to identify faulty electrical connections. In some embodimentsthe current may be applied for fractions of a second as well as one,two, five, ten or more seconds. The applied current may be fractions ofan amp as well as one, two, five, ten, I_(max), or more amps. Thus, afraction of max current of a workpiece or max current of a subsection ofworkpiece, as well as max current itself, and even a multiple of maxcurrent, may each be employed in embodiments when testing usinginfra-red sensors or other thermography sensors. Lock-in thermographytechniques may be employed as well.

In thermal testing as well as other embodiments, when identifying modulelevel electrical connections, for example, current may be sent in aforward bias direction for a period of time, e.g., five seconds, andthen a reverse bias direction for a period of time, e.g., five seconds.An infra-red sensor or other thermography sensor may then read theinfra-red or other thermal signatures of the electrical connections inthe module workpiece and report on whether any connection is faulty andif so which ones. In some embodiments the electrical connections beingtested may be within potting material, such as potting in a junctionbox.

Embodiments may be employed to identify intermittent connections orother faults in connections made during assembly of subcomponents of aworkpiece. For example, internals of PV cells may not be tested inembodiments using thermography. Rather, j-boxes, connections ofgroupings of PV cells to a bus, etc., may be tested using thethermographic or other techniques taught herein. Thermographic testing,such as infra-red testing, may be employed to take advantage of lowresistance shunts or other known connection properties. These lowresistance areas can have higher currents, and corresponding higherthermal outputs. By using forward and reverse bias currents, moreinterconnections can be cordoned and tested with thermography or othertechniques of embodiments.

In embodiments, a testing system manager as well as a human operator mayobserve the infra-red signatures, other thermal signatures, or othertesting methodology outcomes (TDR, Dark IV, mechanical observation) anduse them to determine operational status of one or more electricalconnections in the workpiece. These observations may include thermalobservations, resistance measurements, inductance measurements, in bothreal-time as well as from stored data. These observations may becompared to known benchmarks to determines if a junction being testedmeets or does not meet an expected performance standard. For example, anexpected temperature rating or an expected resistance or an expectedimpedance may be compared to one or more outputs from conducted testing.

As also noted above, measurements may be taken with and withoutpercussive agitation or other testing methodology. Measurements takenwithout percussive agitation or other testing methodology may be takento provide baseline or target voltage readings for properly operationalworkpieces. These target values may then be used for comparison purposesto determine whether a workpiece being tested meets these target valuesor shows an intermittent pathway of some kind using one or more of thetesting techniques taught herein.

The measurement sampling of a workpiece when determining a target value,or for other testing purposes, may occur at frequencies higher than anagitation frequency or other testing frequency. The sampling ispreferably higher than the frequency of testing in order to obtainmultiple samples during a single agitation cycle, TDR electrical signaloscillation, or other testing cycle. Once the voltage or current issampled, the sampling data may be used by a microprocessor to output apass/fail indicator for the workpiece or certain components therein. Thepass/fail indicator may be an audible tone as well as a visibleindicator. Other pass/fail indicators may also be used.

The topology of the workpiece may be considered and used to determinethe type of intermittent failure. For example, certain electricalpathways may be selectively used in PV modules. When only a reverse biastest provides a failure, the selectively used pathways may be indicated.If a diode or junction box is part of the selectively used pathway,reworking the connections therein may be employed to fix or otherwisesalvage the workpiece.

System embodiments may include a power supply, a mobile agitationdevice, a thermographic sensor, and a voltage measurement system. Thesemay be integrated into an end of line tester in a solar module factoryto carry out intermittent connection and diode tests after flash testingand electro luminescence (EL) tests have completed. In use, a powersupply may be applied in a reverse bias on the module or otherworkpiece, and a voltage may be measured. The power supply may also beemployed for dark IV testing and TDR testing. The module or otherworkpiece may then be agitated using a haptic feedback device or othermechanical vibration source and the voltage may be measuredagain—sampled rapidly enough to identify any circuit opening conditionsdue to the vibration of the module. The measured voltage at certainintervals of time may then be compared to baseline values and pass/failcriteria may be applied. In certain photovoltaic cell circuit, laminateand/or module testing embodiments, a voltage of the module at ˜100 mA inreverse may be approximately 2.5V. If this value is much lower or higherthan 2.5V then a failure of diodes may be presumed and if the voltagechanges significantly upon addition of the vibrating motion then it maybe concluded that one of the j-box solder joints is intermittent. Aforward bias of around 100 mA may also be applied in embodiments. Thevoltage may be measured and a vibration may be applied to the module (bytouching the frame with a haptic feedback device or other vibrationsource). If the voltage changes significantly upon agitation a centerlane to bus ribbon solder joint or another electrical pathway may beconsidered intermittent.

Embodiments may be calibrated to test various electrical pathways,including solder joints and mechanical connections. This testing may beperformed on one or more PV laminates and/or PV modules, or otherworkpiece, which may be large and have circuits embedded between glasslayers. When a failure is found, the indicator may specify a portion orcomponent of the PV laminate in certain embodiments or may fail anentire PV laminate in other embodiments. Thus, embodiments may provideend of line module testing to identify intermittent connections and mayalso provide a diode screen that may screen 100% or about 100% or otherportion of the diodes.

In embodiments, forward bias loading may be employed in the samedirection as Electro Luminescence (EL) testing but with a smallercurrent. When testing with reverse bias loading, measurements may betaken before agitation as a benchmark, and after agitation to sense anintermittent connection. As noted above, the sensing should have asampling rate that allows multiple samples to be taken during eachagitation cycle or electrical cycle. In embodiments, the power sourcefor the EL test may also be employed to power the mechanical agitationtesting. The frequencies of agitation may range from tens of cycles perminute to thousands of cycles per second, or more or less. The voltagesemployed may range from micro volts to tens of volts or more or less.

In embodiments, the number of testing stations on a manufacturing linemay be reduced when automatic soldering is used and testing may beconducted immediately after soldering is conducted. Embodiments mayprovide for testing PV laminates before or after potting is injected.Other components, such as frames and junction boxes may already beinstalled when testing is conducted.

As noted above, embodiments may employ rapid voltage sensing. Thissensing may include use of a constant current applied to a workpiece anddetecting voltages before and after agitation is mechanically applied.When agitation is directly applied, a voltage signal change occurs andshould be sampled at a rate faster than the agitation frequency. Forexample, if agitation was applied at 19 Hz then sampling may be taken at190 Hz or some other sampling rate larger than 19 Hz. A sampling rate of10× the agitation frequency may be used as a starting point formeasuring voltage or current fluctuation frequency waveforms althoughother multipliers, such as 2×, 3×, 4×, 5×, 6×, 15×, 20×, etc., may alsobe used.

Embodiments may employ a movable control arm such that an electricalpathway tester may be moved to touch the PV circuit, laminate module orother workpiece being tested. The movement of the control arm may beautomated, semi-automated, and manually controlled. The electricalpathway tester may comprise an exposed direct contact vibrationgenerator, a thermographic sensor, an infra-red sensor, a multiplefrequency voltage generator, and/or other testing apparatus.

The sensors of embodiments may sense variations in voltage on the orderof a few millivolts when a circuit is intact and an open circuit, e.g.,60 v, when a connection is intermittent. Sensed voltages, of tens orhundreds of millivolts, may also indicate an intermittent circuit. Thesemillivolt or larger variations may be indicated visually, through ascreen or readout, or audibly through a speaker. For example, adistorted audio signal can indicate an intermittent connection orotherwise failed workpiece.

As noted, processes may include testing with forward and reversecurrents. The forward sweeps, i.e., testing with current in a firstdiode direction, may include measuring voltage to create a baseline.This baseline voltage may be an alternating voltage as well as a stablevoltage. The workpiece being tested, e.g., a PV laminate, may then beagitated, dark IV tested, TDR tested, or otherwise tested, at an initialbaseline. Measurements of the resulting voltage signal may then be takenat a frequency higher than a baseline testing frequency. This samplingmay occur ten times or more in order to sample resulting voltages afteragitation. When sufficient changes in voltage are detected, anintermittent connection may be considered to have been identified. Thedifference between the sampled voltages and the expected voltages may beon the order of 15%, 20%, 25%, etc. or more or less. This percentagedetected difference may depend on the workpiece being tested, the testcurrent being applied, and the frequency of the agitation, dark IVtesting, TDR, and/or sampling.

As noted above, a reverse sweep may also be conducted. This reversesweep may provide current flowing in the opposite direction, i.e.,opposite the first diode direction. The testing may be conducted in thesame fashion but may indicate that a different portion of the workpiecehas an intermittent connection when a failure is detected. In otherwords, by changing the direction of current flow different portions ofthe workpiece, which may not be accessible under the first current flowdue to diodes or other circuit topologies, may be tested in a reversecurrent situation. And, by conducting testing with both forward bias andreverse bias portions of the workpiece, e.g., the PV laminate, may beidentified as failing. For example, junction box connections notaccessible under a forward bias test may be identified with a reversebias test. Likewise, a center bus solder joint problem can be confirmedusing forward and reverse bias flows when the topology of a center busprovides for different current flows under the forward and reversecurrent bias flows.

Embodiments may provide an electrical pathway intermittent faultdetection system comprising an electrical pathway tester having at leastone of an exposed direct-contact vibration generator, a thermal sensor;or a multiple-frequency voltage generator; an exposed electrical sensor;an electrical power supply; and a microcontroller. The microcontrollermay be configured, using outputs from the electrical pathway tester, todetermine whether an intermittent electrical pathway is present in apotted junction-box of the photovoltaic laminate and to provide a signalwhen an intermittent electrical pathway is detected. In some embodimentsthe vibration generator may be configured to generate vibrations acrossa range of frequencies, and the power supply may be configured toprovide electrical power to the vibration generator. In someembodiments, the microcontroller may be configured to consider thepresent frequency of vibration of the vibration generator when thevibration generator is in contact with a photovoltaic laminate, andfurther configured to consider voltages sampled from the photovoltaiclaminate when the vibration generator is in contact with thephotovoltaic laminate, the sampling rate of considered voltages beingfaster than the present frequency of vibration. In some embodiments, themicrocontroller may be further configured to compare the voltagessampled with target voltages, to determine whether an intermittentelectrical pathway is present in the photovoltaic laminate and toprovide a signal when an intermittent electrical pathway is detected.

Embodiments may sometimes comprise a shared bus, the shared bus coupledto two or more of: the vibration generator, the voltage sensor, thepower supply, and the microcontroller. In some embodiments, a presetfrequency of vibration may be set to one-tenth or less of the frequencyof the sampling rate of considered voltages and in some embodiments thetarget voltage is predetermined, calibrated for the photovoltaiclaminate, and is in a range of 0.002 volts to 20 volts.

In some embodiments, the voltages sampled from the photovoltaic laminateresult first from a forward bias current and from a reverse biascurrent, the current provided by the power supply, the forward biascurrent used to detect soldering failure in the photovoltaic laminate,the reverse bias current used to detect diode failure in thephotovoltaic laminate. And, the signal, when an intermittent electricalpathway is detected, may be an audible frequency in the range of 20 Hzto 20,000 Hz. Still further, in some embodiments, the vibrationgenerator may be mounted on an automated arm.

Some embodiments may comprise an electrical pathway intermittent faultdetection device comprising a thermal imaging sensor; an electricalsensor; an electrical power supply; and a microcontroller. Thismicrocontroller may be configured to apply a forward bias currentthrough a potted electrical connection for a first period of time and toapply a reverse bias current through the potted electrical connectionfor a second period of time. The microcontroller, in embodiments, mayalso be configured to report information observed by the thermal imagingsensor during the first period of time and during the second period oftime.

In some embodiments, the workpiece is a photovoltaic laminate and thepotted electrical connection resides in a junction box. And in someembodiments, the thermal imaging sensor is an infra-red sensor. Stillfurther, in some embodiments the electrical connection being tested hasa maximum current and the forward bias current and the reverse biascurrent do not exceed the maximum current. The first period of time andthe second period of time do not overlap in some embodiments and areeach no longer than ten seconds in some embodiments. Sometimes, thefirst period of time occurs after the second period of time andsometimes, the first period of time occurs before the second period oftime.

Embodiments may also include a process of electrical pathwayintermittent fault detection comprising providing an exposeddirect-contact vibration generator, a thermal sensor; or amultiple-frequency voltage generator; providing a plurality ofelectrical sensors; providing an electrical power supply; and providinga microcontroller. The microcontroller may be configured to determinewhether an intermittent electrical pathway is present in a pottedjunction-box of a photovoltaic laminate and to provide at least anaudible or visual signal when an intermittent electrical pathway isdetected. In embodiments the vibration generator and the thermal sensormay be mounted on an automated arm. This automated arm may be configuredto receive instructions from the microprocessor in some embodiments.

Embodiments may further comprise applying a forward current bias to thephotovoltaic laminate and applying a reverse current bias to thephotovoltaic laminate. In some embodiments, the forward current bias andthe reverse current bias may be applied for the same duration of timebut not applied during the same time period.

FIGS. 1 and 2 show a photovoltaic laminate 100 workpiece as may beemployed for testing in embodiments. Each workpiece has six hyper cells101 in parallel to comprise the laminate 100. These hyper cells 101 areseparated into three diode sections, the sections lay between trace 102and 103, trace 103 and 104, and trace 104 and 105. These sections areelectrically separated by diodes 106-108. These sections may beconnected to junction boxes (which are not shown) and through junctionboxes, to the center lane 110. Several non-redundant solder joints areassociated with the center lane and the junction boxes electricallyconnected to the center lane. The diode junctions 111 can be areas ofinterest to be tested in embodiments. These junctions can includeelectrical connections made during assembly of the laminate 100, whichhave gone previously untested.

FIG. 1 illustrates a schematic of a laminate photovoltaic 100 workpieceunder forward bias testing according to some embodiments. Thick lines120 indicate electrical pathways for different types of tests. In theforward bias test of FIG. 1 current is passing through all of the cellsand hitting the four joints of the module's four solder joints. There isno parallelization or redundancy if a joint is not functioning. FIG. 2illustrates a schematic of a laminate photovoltaic 100 workpiece underreverse bias testing according to some embodiments. The positions of avibration generator are also shown. With position A indicating contactwith the workpiece laminate and position B indicating a spacing betweenthe workpiece laminate and the vibration generator. In the reverse biastest, which is shown in FIG. 2, the cells are avoided while thejunctions are being tested for intermittent or otherwise faultyconnections.

The positions A and B of a vibration generator are shown in FIGS. 1 and2. Also labelled in these figures are diode junction 111, bypass ribbons126, edge diode 106, solder joints 125, testing system manager 140,sensor inputs 141, inputs/outputs 142, control arm 150,thermal/infra-red camera/sensor 160, inputs/outputs 161, positive sensorlead 128, and negative sensor lead 127.

Position A in FIGS. 1 and 2 indicate contact with the workpiece laminateand position B indicates a spacing between the workpiece laminate andthe vibration generator. The control arm 150 is shown schematically. Thecontrol arm 150 may be positioned to move one or more sensors ofembodiments during testing protocols and may also serve to move or stowa testing system manager. The testing system manager 140 may beconfigured to control portions or all of the loading, sensing, andmovement operations of embodiments and other features described ortaught herein. The system manager may be configured in a single deviceor across multiple devices. The system manager may control appliedcurrents to the laminate 100 or other workpiece and may receive outputsfrom cameras/sensors in embodiments. The manager may use these receivedoutputs to identify any intermittent or complete faults in the laminateor other workpiece. These faults may be located at solder joints orother connections both within and outside of potted j-boxes.

As another example, FIG. 9 illustrates a schematic of a laminatephotovoltaic 900 workpiece as may be employed in some embodiments. Inparticular, FIG. 9 shows the back side of the PV module 900 and includesan array (e.g., a 6×8 array) of PV cells 982. At one end of each columnof cells 982, busbars 900 and 920 couple the columns of cells 982 to ajunction box 984 coupled to the PV module 980. At the opposite end ofeach column of cells 982, formed cell connection pieces 902 couple pairsof columns together to connect two columns of cells in series connectedstring of cells. These series-connected strings of cells may beconnected to junction box 984. These cell connection pieces or busbars900 and 920, and/or diodes of junction box 984 can be areas of interestto be tested in embodiments. Connection pieces 902, which have parallelredundant connections may be skipped from testing or selectively testedin embodiments because the redundant connections can serve to deterspecific testing of a single connection. For example, in someembodiments, single connection points are sought to be isolated fortesting so that a test pass or failure can be attributed to a singleconnection. When a component has two or more connections that can't beindividually isolated, these components may or may not be the target ofembodiments depending on the level of specificity sought for the testingbeing conducted. Thus, if an entire component can be reconnected, forexample, it may be tested even if each of the connections for thecomponent can't be isolated for testing using the techniques taughtherein.

FIG. 3 illustrates workpiece testing process elements as may be employedin some embodiments. Label 310 provides that embodiments may includepositioning a workpiece into a test area. This positioning may becompleted manually or with automation, and may occur during manufacture,near the completion of manufacture as well as prior to installation. Theworkpiece may be a photovoltaic laminate with multiple solderedelectrical connections or mechanical electrical connections as well asother devices with soldered electrical connections or mechanicalelectrical connections. Label 320 provides that embodiments may includeconducting forward electrical current bias testing of a workpiece usingone or more testing methods (e.g., Time Domain Reflectometry (TDR),mechanical agitation, current/voltage loading (dark IV), andthermal/infra-red inspection). These testing methods may be conducted invarious sequences and in some embodiments only one or two or three ofthe methods may be used. The forward current bias may be provided andmanaged by a testing system manager. Likewise, the testing and analysismay be conducted by a testing system manager. Label 330 provides thatembodiments may include conducting reverse electrical bias testing usingone or more testing methods (e.g., Time Domain Reflectometry, mechanicalagitation, current/voltage loading, and infra-red inspection). Like 320,the reverse electrical bias testing may be conducted by the testingsystem manager using one or more of the testing methods. Label 340provides that embodiments may include determining the adequacy of one ormore electrical connections in workpiece being tested and label 350indicates that these determinations can lead to passing or failing oneor more electrical connections in workpiece using one or more of thetesting methods. As shown at 360, if failure occurs under one or moretesting methods, the testing system manager may make a recommendation ora determination as to whether or not to repair or discard the workpiece.As shown at 370, if a workpiece passes, the workpiece may be identifiedas suitable for a next manufacturing step, shipment, and/orinstallation.

FIG. 4 illustrates process elements for time domain reflectometry (TDR)workpiece testing as may be employed in some embodiments. As shown at400 embodiments may begin by connecting a workpiece for TDR testing.Afterwards, as shown at 410, one or more oscillating signals of a singlefrequency or multiple oscillating signals at differing frequencies (i.e.spread spectrum) may be generated and placed on the workpiece. As shownat 420/430 embodiments may also include placing forward electrical biason the workpiece and observing reflected signals as well as placingreverse electrical bias on the workpiece and observing reflectedsignals. As shown at 440, observed reflected signals, may be used todetermine operational status of one or more electrical connections inthe workpiece and if failure occurs, under one or more testing methodsdetermine whether to repair or discard workpiece, as shown at 450.Comparatively, as shown at 460, if the workpiece passes, the workpiecemay be identified as suitable for a next manufacturing step, shipment,and/or installation.

FIG. 5 illustrates process elements for non-illumination current/voltage(dark IV) workpiece testing as may be employed in some embodiments. Asshown at 500 a workpiece may be connected for non-illuminationcurrent/voltage testing. Once connected, test current or test voltagemay be applied across one or more diodes of the workpiece, as shown at510. As shown at 520, a forward electrical bias may be placed on theworkpiece followed by observation of any changes in applied current orvoltage. Similarly, but in reverse, as shown at 530, a reverseelectrical bias may also be placed on the workpiece followed byobservations of any changes in applied current or voltage during thistype of loading. As shown at 540, observed changes in current orvoltage, may be observed in order to determine operational status of oneor more electrical connections in the workpiece. As shown at 550, iffailure occurs under one or more testing methods a determination may bemade as whether or not to repair or discard the workpiece. As shown at560, if the workpiece passes, it may be identified as suitable for anext manufacturing step, shipment, and/or installation.

FIG. 6 illustrates process elements for infra-red workpiece testing asmay be employed in some embodiments. As shown at 600, a workpiece may beconnected for Infra-Red or other thermal spectrum testing. Onceconnected, as shown at 610, a forward bias electrical current may beplaced on workpiece and infra-red or other thermal signatures may beobserved of one or more electrical connections being tested. Also, at adifferent time, as shown at 620 a reverse bias electrical current mayalso be placed on the workpiece and infra-red or other thermalsignatures may be observed of one or more electrical connections beingtested. A testing system manager as well as a human operator may observethe infra-red signatures or other thermal signatures and use them todetermine operational status of one or more electrical connections inthe workpiece. These observations may include thermal observations,resistance measurements, inductance measurements, in both real-time aswell as from stored data. These observations may be compared to knownbenchmarks to determine if a junction being tested meets or does notmeet an expected performance standard. For example, an expectedtemperature rating or an expected resistance or an expected impedance.As shown at 640, if a failure occurs under one or more testing methods,a determination as to whether or not to repair or discard workpiece maybe made. Comparatively, as shown at 650, if a workpiece passes, theworkpiece may be identified as suitable for a next manufacturing step,shipment, and/or installation.

FIG. 7 illustrates process elements for mechanical agitation workpiecetesting as may be employed in some embodiments. This figure shows thatembodiments can include applying a forward bias (710) measuringresulting voltage (720) and determining a baseline voltage (730).Afterwards, a testing methodology may be applied, here mechanicalagitation (740), followed by testing at a sampling frequency at least10× greater than the applied voltage frequency and changes in voltagesare observed (760). A reverse bias may also be applied (770) followed bymeasurements (780) and a determination of baseline voltages (790). Beinga reverse bias direction, the baseline voltages are reflective of diodefunction. Mechanical agitation (791) or other testing methodology fromherein may follow the baseline determination. Testing at a samplingfrequency at least 10× greater than the applied voltage frequency andchanges in voltages are observed (793).

FIG. 8 illustrates an exemplary testing system manager 800 according tosome embodiments. The testing system manager 800 may be employed in asingle device or across multiple devices. The system manager 800 mayinclude one or more connection buses 894 as well as multiple frequencyvoltage generator 810, power supply 820, microcontroller 830, RAM/ROM840, voltage and current sensors input/output 891, voltage measurementmodules 850, current measurement modules 850, output and readoutcomponents 892, input/output controls 860, thermal/infra-red sensorsinput/output 870, storage 880, vibration generator 890, and movementcontrol module 893. The output and readout components may includeoptical displays, screens, and audio speakers. The storage 880 may storeinstructions for the microcontroller 830 to perform one or more of theactions described herein. These may include sending bias voltages andcurrents, reading sensor inputs, providing instructions to sensors,providing instructions for movement, providing outputs and the variousother actions and processes and functions taught herein.

Although specific embodiments have been described above, theseembodiments are not intended to limit the scope of the presentdisclosure, even where only a single embodiment is described withrespect to a particular feature. Examples of features provided in thedisclosure are intended to be illustrative rather than restrictiveunless stated otherwise. The above description is intended to cover suchalternatives, modifications, and equivalents as would be apparent to aperson skilled in the art having the benefit of this disclosure.

The scope of the present disclosure includes any feature or combinationof features disclosed herein (either explicitly or implicitly), or anygeneralization thereof, whether or not it mitigates any or all of theproblems addressed herein. Accordingly, new claims may be formulatedduring prosecution of this application (or an application claimingpriority thereto) to any such combination of features. In particular,with reference to the appended claims, features from dependent claimsmay be combined with those of the independent claims and features fromrespective independent claims may be combined in any appropriate mannerand not merely in the specific combinations enumerated in the appendedclaims.

What is claimed is:
 1. An electrical pathway intermittent faultdetection system comprising: an electrical pathway tester comprising amechanical vibration generator; an exposed electrical sensor; anelectrical power supply; and a microcontroller, wherein themicrocontroller is configured, using outputs from the electrical pathwaytester, to determine whether an intermittent electrical pathway ispresent in a junction-box of the photovoltaic laminate and to provide asignal when an intermittent electrical pathway is detected, and whereinthe microcontroller is further configured to consider a frequency ofvibration of the mechanical vibration generator applied to thephotovoltaic laminate by the mechanical vibration generator, and furtherconfigured to consider voltages sampled from the photovoltaic laminate,the sampling conducted when the mechanical vibration generator is incontact with the photovoltaic laminate, the sampling rate of consideredvoltages being faster than the frequency of vibration of the mechanicalvibration generator.
 2. The system of claim 1 wherein the mechanicalvibration generator is configured to generate vibrations across a rangeof frequencies, wherein the power supply is configured to provideelectrical power to the vibration generator, and wherein themicrocontroller is further configured to compare the voltages sampledwith one or more target voltage, to determine whether an intermittentelectrical pathway is present in the photovoltaic laminate and toprovide a signal when an intermittent electrical pathway is detected. 3.The system of claim 2 further comprising a shared bus, the shared buscoupled to two or more of: the mechanical vibration generator, thevoltage sensor, the power supply, and the microcontroller.
 4. The systemof claim 2 wherein the frequency of vibration of the mechanicalvibration generator is one-tenth or less than the frequency of thesampling rate of considered voltages.
 5. The system of claim 2 whereinthe one or more target voltage is predetermined, calibrated for thephotovoltaic laminate, and is in a range of 0.002 volts to 20 volts. 6.The system of claim 2 wherein voltages sampled from the photovoltaiclaminate result first from a forward bias current and then from areverse bias current, the current provided by the power supply, theforward bias current used to detect soldering failure in thephotovoltaic laminate, the reverse bias current used to detect diodefailure in the photovoltaic laminate.
 7. The system of claim 2 whereinthe signal when an intermittent electrical pathway is detected is in anaudible frequency range of 20 Hz to 20,000 Hz.
 8. The system of claim 2wherein the mechanical vibration generator is mounted on an automatedarm.
 9. An electrical pathway intermittent fault detection devicecomprising: a thermal imaging sensor; an electrical sensor; anelectrical power supply; and a microcontroller, wherein themicrocontroller is configured to apply a forward bias current through anelectrical connection of a workpiece for a first period of time and toapply a reverse bias current through the electrical connection of theworkpiece for a second period of time, wherein the microcontroller isfurther configured to report information observed by the thermal imagingsensor during the first period of time and during the second period oftime, and wherein the microcontroller is further configured to considera frequency of vibration of a mechanical vibration generator applied tothe workpiece by the mechanical vibration generator, and furtherconfigured to consider voltages sampled from the workpiece, the samplingconducted when the mechanical vibration generator is in contact with theworkpiece, the sampling rate of considered voltages being faster thanthe frequency of vibration of the mechanical vibration generator. 10.The device of claim 9 wherein the workpiece is a photovoltaic laminateand the electrical connection resides in a potted junction box.
 11. Thedevice of claim 9 wherein the thermal imaging sensor is an infra-redsensor.
 12. The device of claim 9 wherein the electrical connection hasa maximum current and the forward bias current and the reverse biascurrent do not exceed the maximum current.
 13. The device of claim 9wherein the first period of time and the second period of time do notoverlap and are each no longer than ten seconds.
 14. The device of claim9 wherein the first period of time occurs after the second period oftime.
 15. The device of claim 9 wherein the first period of time occursbefore the second period of time.
 16. A process of electrical pathwayintermittent fault detection comprising: providing an exposeddirect-contact vibration generator; providing a plurality of electricalsensors; providing an electrical power supply; and providing amicrocontroller, wherein the microcontroller is configured to determinewhether an intermittent electrical pathway is present in a junction-boxof a photovoltaic laminate and to provide at least an audible or visualsignal when an intermittent electrical pathway is detected, and whereinthe microcontroller is further configured to consider a frequency ofvibration of the direct-contact vibration generator applied to thephotovoltaic laminate by the direct-contact vibration generator, andfurther configured to consider voltages sampled from the photovoltaiclaminate, the sampling conducted when the direct-contact vibrationgenerator is in contact with the photovoltaic laminate, the samplingrate of considered voltages being faster than the frequency of vibrationof the direct-contact vibration generator.
 17. The process of claim 16wherein the direct-contact vibration generator is mounted on anautomated arm.
 18. The process of claim 17 where the automated arm isconfigured to receive instructions from the microprocessor.
 19. Theprocess of claim 16 further comprising applying a forward current biasto the photovoltaic laminate and applying a reverse current bias to thephotovoltaic laminate.
 20. The process of claim 19 wherein the forwardcurrent bias and the reverse current bias are applied for the sameamount of time but not applied during the same time period.